The client on this project wanted the most room possible inside the shower niche. To achieve this we simply installed backer board onto the back side of the opposite rooms drywall (in the kitchen). This of course is outside any industry recommendation but done all the time building a shampoo niche.
To set the Denshield to the drywall back I used nothing but a little thin-set and then braced it overnight. After the shower walls where boarded and waterproofed we set the back tile tight, tight, tight.
I had some left over 8+9 Waterproofing and wondered if I could set a tile with it - so I tried!!! Worked like a champ and the tile is set perfectly 4mm above the desired grout joint.
Here you can see the 8+9 slurried on my tile back.
The laser is set to the bottom of the tile for easy reading. A few shims and the tile was good to be left alone.
The next step was installing the face tiles and the two sides. To have something to support the tile I screwed in a few scrap pieces of wood. It is very important to patch these holes later. The Ardex 8+9 waterproofing allows me to do two coats in the same day (half day really).
You can see by the measurement on my Chubby (Pencil ruler) that the thin set is a good inch. Very few thin sets can achieve this. Make sure if you are using a regular thin-set that the thickness does not exceed 1/4" in total.